RE: USA 129 orbit raise?

From: Ted Molczan (molczan@rogers.com)
Date: Thu Jun 17 2004 - 18:46:52 EDT

  • Next message: Skywise: "Re: Possible re-entry?"

    Bjorn Gimle wrote:
    
    > Pierre said in a DSat message: This evening,interval 96-72A/01-44A 
    > should be 2h47.3. Do they wait that W part of Europe completely 
    > overcast to perform their pending manoeuvre ?
    > 
    > Since the KH orbits are elliptical, and do not have their 
    > perigees in the "same" orbital longitudes, the separation in 
    > time varies with position in orbit.
    > 
    > In my message to DSat 2004-06-13 I proposed a theory that the 
    > southbound daylight pass is more significant to determine the 
    > time of maneouvre. In that case 2:45 is reached on June 19, 
    > using the elsets available at that date. I doubt new elsets 
    > would change the time by more than a few hours earlier.
    > 
    > I have not verified with earlier occasions, but I know it 
    > gave a better result at least once.
    
    I have reviewed all of the USA 129 (96072A / 24680) reboosts during the life of
    USA 164 (01044A / 26943) for which I have orbital elements. The results are
    summarized below:
    
                                 01044A lag
    96072A boost  UTC     Lat      h:mm:ss
    ---------------------------  ----------
    2002 Apr 04  16:27  00.17 S   +2:41:41
    2002 Jun 27  15:09  81.45 N   +2:40:31
    2002 Sep 12  16:35  14.52 S   +2:45:44
    2003 Jan 17  14:03  39.72 N   +2:39:00
    2003 Mar 27  15:46  81.39 S   +2:46:00
    2003 Jun 05  18:44  42.13 N   +2:40:39
    2003 Aug 07  13:58  16.61 S   +2:37:09
    2003 Oct 16  14:33  31.89 S   +2:48:44
    2003 Dec 18  12:54  57.99 N   +2:42:16
    2004 Feb 12  17:34  60.42 N   +2:44:06
    2004 Mar 18  17:43  06.00 S   +2:42:31
    2004 Mar 23  14:16  09.74 N   +2:42:16
    
    The reboost times ranged between 12:54 and 18:43 UTC, about a 6 hour span, that
    seem to fit nicely into someone's 8 h workday.
    
    Lat is USA 129's latitude at the time of the boost. 2004 Feb 12 was at apogee;
    all others at perigee.
    
    01044A lag is the amount by which its ascending node (northbound equator
    crossing) time lags that of USA 129, when it nearly repeats USA 129 ground
    track. The range was +2:37:09 to +2:48:44.
    
    Today (Jun 17 UTC) the lag was about +2:47, and it is growing at the rate of
    about 1 min/d, so if the boost did not occur today, then tomorrow or the next
    day seem likely.
    
    It is cloudy here, and unlikely to clear tonight.
    
    Ted Molczan
    
    
    
    
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